Growth-inhibitory activity of phenolic compounds applied in an emulsifiable concentrate - ferulic acid as a natural pesticide against Botrytis cinerea.

Phenolic compounds are part of the protection system of plants against all kinds of pests and are therefore considered a natural alternative to conventional plant protection agents. Five phenolic compounds (phlorizin, resveratrol, ferulic acid, 5-n-alkylresorcinols, and quercetin) were used as active ingredients in the preparation of a bioactive emulsion and screened for their ability to inhibit the growth of four phytopathogenic fungi - Aspergillus niger, Botrytis cinerea, Penicillium expansum, and Fusarium culmorum. By using design of experiments, several interactions between the phenols were determined, however, ferulic acid was identified as highly effective against the growth of Botrytis cinerea. The growth-inhibitory effect of this emulsion was enhanced by adapting the ferulic acid concentration (0.085%, m/v) with the help of response surface methodology. Subsequent tests confirmed the activity against the growth of nine fungicide-resistant Botrytis cinerea isolates and showed promising results against the infection of injured and contaminated grapes.